The overall objective of the proposed research is to bring to the clinical market an innovative blood reservoir system that accurately measures and displays the volume in the blood reservoir used at the inlet of the pump during cardiopulmonary bypass. A second objective is to provide a signal that can be used to regulate roller pump flow to match venous return. No system currently in use provides a continuous measure of reservoir volume or a means of obtaining flow from changes in reservoir volume. The proposed system weighs the reservoir with a uniquely designed mechanism that minimizes errors inherent in other weighing devices. The basic components of the system include a disposable reservoir and electronic scale. The proposed system would significantly improve both the safety and operability of present cardiopulmonary bypass procedures without additional costs. PROPOSED COMMERCIAL APPLICATION: The annual world-wide market for the disposable reservoir in cardiopulmonary bypass procedures is over 650,000. The total potential market for the proposed weighing system equals the number of heart-lung consoles in use, currently over 2,000. Other applications, such as rapid infusion or blood salvage systems, further expand the market for the device. The price of the disposable would be the same or lower than that of present reservoirs. The technology devolved to regulate pump flow with venous return may also be licensed to pump manufacturers for use with their automated pumps.